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Frequently Asked QuestionsBelow are answers to common or important questions.
BasicProjectionProduct ComparisonsSoftware FeaturesInflatable DomesGeneralPurchasingBasicWhat does it mean that your systems are digital? Why is that important?A digital planetarium system is a computer based system using digital projection, as opposed to an analog type pin-hole or lens based projection system. It is a huge difference, because a computer based system is so much more flexible than an analog system. Think of the difference between a computer and a slide projector and you start to see the power of a digital system. In a digital system, the projected image is made up of individual pixels. Because the dome is covered by an array of pixels rather than a fixed set of holes or lenses, anything can be projected: views from other planets, videos, images, other applications. Analog systems can often produce smaller stars and higher contrast ratios, but without any of the flexibility of digital systems. So unless your goal is to try to match the night sky as closely as possible, and nothing more, you really need a digital planetarium system. For more detail, see How does a Digitarium system compare to an analog Starlab projector?. I want to build a planetarium. Where should I start?
Can I rent a system for my school or birthday party?We do not offer system rentals, however there may be an outreach program near you that could meet your needs. ProjectionCan the same projection system be used in domes of different sizes?Yes. The lens has almost infinite depth of field, which means there are no focus issues due to differing dome sizes, although brightness is an issue:What is the maximum dome size recommended for a Digitarium system?It depends on the Digitarium model. Details are on this page. Dual lamp models are brighter and can work in larger domes. With a dual lamp system in a smaller dome you can either have brigther projection, or use just one lamp and keep the other on standby for automatic failover. Your dome surface and projection content will also play a role in determining what model is acceptable. What is the minimum dome size for a Digitarium system?Approximately 1 foot/30 cm in diameter.Will stars be larger on a larger dome?At the surface of the dome each pixel will be physically larger on a larger dome. However, angular pixel dimensions do not change with dome size, so on average pixels do not appear larger to an audience. Someone sitting next to the side of the dome will obviously see larger pixels nearby than on the opposite side of the dome due to their perspective. Someone seated near the middle would not notice any difference other than brightness between domes of different sizes.How high a contrast ratio do I need?In a planetarium, it is somewhat distracting if the dark areas of a starfield are a dark gray rather than a full black. How black the dark areas appear depends on a number of factors, including the contrast ratio of your projector. The contrast ratio of a projector is the ratio of the luminance of a white projection compared to a black projection. Digital projectors usually have much lower contrast ratios than analog projectors, which is just inherent to the technology differences. The higher the contrast ratio, the darker the black areas are compared to the bright areas. With a low contrast ratio, blacks appear as dark gray rather than true black. A number of LCD digital planetarium systems have a contrast ratio of 400:1. The Digitarium Gamma has a measured minimum contrast ratio of 2100:1 in dual lamp mode. The Digitarium Epsilon is slightly better. When comparing systems, ask whether the contrast ratio quoted was actually measured with the lens you would be using on the projector. Also be aware that there is a tradeoff between projection brightness and contrast so you usually can't get the highest contrast and highest brightness at the same time. Usually a digital projection system is used with a light gray dome surface to enhance the black level. The light grey is less reflective than a traditional white dome, and thus darkens the projection and reduces the luminance of the black areas. Since the black level is more noticeable than the actual contrast ratio, this tends to be a good solution. The gray color further reduces cross-reflection on the dome, when a bright image on one side of the dome reflects across the dome and washes out darker areas. Another option to adjust the black level is just to turn the projector lamp down to low. As you would expect, the dome size also will affect the black level seen by the audience. In summary, it is the black level luminance perceived by the audience that is what you should focus on, although selecting an acceptable level is subjective. The projector contrast ratio affects the black level, but there may be more cost effective ways to achieve the same effect with a lower contrast system. If I project a rectangular image, movie, or PowerPoint through your projector, what will it look like?Fisheye projectors will introduce a large amount of distortion if you project a standard perspective image or application at full projector resolution. By distortion we mean that the projected image is deformed from its natural shape. In a Digitarium system a central circular area of the video source is projected onto the dome. The outer rim of the circle is projected at the horizon, and the center of the image is the zenith (top of the dome). This is called a polar projection. If you projected a PowerPoint slide full of text at full projector resolution, you would see your text cover the entire dome, but half of it would be upside down as it wraps past the zenith. However, since Digitarium systems with our current operating platform, Digitarium OP3, perform dynamic distortion correction, you do not need to worry about this. Simply display your image in perspective projection mode. You can adjust the size, orientation, and placement of the image or video on the dome, and even mirror it on two sides of the dome for easier viewing by your audience. If you have a fisheye image or fulldome video, simply switch to fulldome projection mode with one button press. Unlike some competing systems, you can easily go from media file to media file for a slide show type use, choose other drives or directories with a visual menu, or switch back and forth seamlessly between your media and the sky simulation. All of this is at your fingertips with our unbelievably easy to use remote control. While we are on this subject, we should point out that fulldome applications and content are designed to immerse the audience in a 3d environment -- it is not possible to add this extra dimension to regular perspective content after the fact. So while you can show distortion corrected perspective content on the dome, it will not be the same as showing immersive fulldome content. Is your lens distortion free?(Be sure to read the above question and answer also.) As an affordability tradeoff, our lens varies slightly from an ideal linear polar distortion. In most cases this will not be noticeable. The following two images illustrate this slight distortion (in this case for the discontinued Digitarium Alpha 2). If the first image was projected through the projector over the whole dome without any distortion correction, it would end up looking like we had projected the second image through an ideal distortion lens.
  Pacific Science Center, Seattle As you can see, the distortion is subtle. Your audience will generally experience a lot more distortion simply due to their perspective away from the center of the dome (where distortion due to perspective is zero). On our current operating platform, Digitarium OP3, dynamic distortion correction is performed on all content, so you will not see any lens distortion. The slight variation in pixel sizes across the dome is not noticeable. If you need exact distortion for a custom fulldome application we can supply distortion functions. Do I need a 3d stereo projector for an immersive experience?No. There is a lot of hype around stereoscopic 3d dome projection systems. The audience must wear special glasses in order for each eye to see slightly different images, which produces the 3d effect. We feel this is mostly another way for vendors to sell more hardware. A dome is already an immersive 3d environment, so there is no need to add awkward glasses and ever more complex hardware. Part of what makes the dome such a wonderful immersive experience is that you are not encumbered by any special equipment that restricts your field of view or movement. Add to this the benefit of experiencing this in a group setting. Any kind of motion on screen will produce the clear illusion of depth, and stereoscopic vision is not even required. Where do I put my projection system in a fixed dome?Ideally a Digitarium system is placed in the center of the dome, whether fixed or portable. However, our current operating platform, Digitarium OP3, can support distortion correction for some amount of lens offset from the center of the dome to work around an existing starball or other obstacle. We now offer an optional elevator mount system for our fixed dome Digitarium Gamma and Epsilon models. Please contact us for more details. Here are diagrams explaining how to calculate typical projector placement:
Product ComparisonsWhat are the main differences between your Digitarium models? Do they do different things?All of our Digitarium models run the same software and have the same basic functionality. The main differences between the models are brightness, resolution, and projection quality. Some models have specific portable or fixed dome configurations, meaning that you need to select which configuration you need. Read more about the different models. Why are your systems so expensive?
Why are your systems so inexpensive?
Aren't there some patents related to fisheye projection?There are a number of broad patents related to hemispherical projection systems. We do not believe that any of our products infringe on any valid patent claims in this area. As a precaution, we also have IP defense insurance coverage so that we can fully defend ourselves should the need ever arise. How can your systems be the best value when there are other systems on the market at similar or lower cost?We believe our Digitarium systems offer the best value on the market for serious astronomy educators. While we have quite affordable prices compared to many other vendors, prices can only go so low without seriously cutting corners. There are some bad systems out there that sound (and are) too good to be true. Think of it this way: would you buy a $500 car? A $500 car is extremely affordable. It probably looks bad, runs on the rough side, and you never know if it will take you where you want to go. The price per pound of such a car is amazing! Maybe 20 cents a pound. But let's face it, at best this is an option for those who can not afford something that looks better, runs better, has lower maintenance costs, features like air conditioning, a warranty, etc. Although extremely affordable, who would confuse a $500 car with being a good value? And yet this mistake occurs all the time, and sometimes in the planetarium world, where affordability is confused with value. You can get the cheapest system on the market, but it almost certainly is not the best value for your money. Conversely, you also don't need a $200,000 Ferrari to commute to work. Value, of course, depends on your specific needs and uses. Figure out which characteristics are most important to you, then do your homework. See a few competing systems, try operating them, and speak to other customers before you decide if each system fits your needs. Comparing systems based on things like the cost per pixel is as ridiculous as using price per pound when shopping for a car. Just as the quality and engineering of the components that make up the mass of a vehicle are what matter, it is the quality of the projected pixels and the features and support behind the system that matter, not how many total pixels there are per dollar. This is counter-intuitive for most people, but a lower resolution, sharply focused image in fact looks much better than an image with, for example, twice as many pixels that are blurry, distorted, or dim. Below is an example of an even more extreme 4:1 resolution ratio (yes, that is a Ferrari). 
The best value is logically the system that gives you the largest benefits at the lowest total cost of ownership. Do not neglect support and maintenance costs down the road. Like a $500 car, affordable sometimes just means cheap.
How does a Digitarium system compare to a spherical mirror projection system?Spherical mirror dome projection systems, such as MirrorDome developed at Swinburne University in Australia, consist of a portion of a spherical mirror, a data projector aimed at the mirror, and a computer running specialized software. The software has to "warp" each video frame before sending it to the projector in order to counteract the severe distortion from the mirror. After reflecting off the mirror images are projected onto a dome. Spherical mirror systems:
Warping artifacts arise when an original source video frame is warped and some detail has to be compressed, resulting in reduced image quality. This is more noticeable with starfields than with videos or images. Here is an illustration:  
The constellation lines have some odd warping artifacts, but also some of the dimmer stars are now almost invisible. Note that these are screenshots from the video frame before it even gets projected. Quality on the dome will depend on many factors, including the software you are using and how it is configured. Digitarium systems:
Using a spherical mirror for planetarium projection has a number of drawbacks. In particular we would highlight the typical lack of full sky projection, lack of crisp focus, and bulky setup. Plus you miss out on the many benefits of a Digitarium, including the uniquely easy to use handheld remote control interface and absence of software maintenance headaches. For astronomy educators the sheer number of pixels projected is simply not the most important feature of a planetarium system. A spherical mirror is an option to consider only if a fisheye planetarium system is out of reach. In that case you might put together your own system for a fraction of the cost of a pre-assembled system. Nightshade planetarium software, which we help develop, is free and already includes a spherical mirror warping mode. So all you need is a mirror, a compatible projector, a computer, and time to put it together. Here is a FAQ on the subject. If you opt for a commercial spherical projection system, make sure it is bright enough for your dome size in the contrast mode you intend to use and that the warping is configured for your dome (to avoid distorted projection). We have seen some providers cutting corners with these types of systems. We highly recommend that you compare a few competing planetarium systems in person before making a purchasing decision. Be sure to insist on a written return policy with any commercial system so that you have an opportunity to return it if you are not happy with it! Why is a Digitarium system a better value than a higher resolution spherical mirror type system?While some Digitarium systems cost more than higher resolution spherical mirror systems, we believe that the following characteristics provide a much better value for serious astronomy educators (see also the above two questions):
So you can see why we believe we have the best value for an educational planetarium system. While it's easy to focus on resolution or up front costs when evaluating competing systems, it's very important to consider the true benefits and costs of ownership for your intended use. We strongly recommend that you see a few competing systems in person and try using them yourself (really!) before making a purchase decision. We don't want to see more people make mistakes that are preventable with a little extra effort up front. It's just a fact that many systems can sound better on paper than they actually perform in the real world. Want to see a Digitarium system near you? What does it mean that some competing systems have truncated projection?Systems with a truncated projection do not project over a full hemispherical dome -- some portions of the sky are not projected. Usually truncation is a tradeoff to reduce costs or improve resolution in the areas that are projected. Digitarium Systems are true full-dome systems and project the entire sky with a full, uninterrupted horizon onto a dome. We feel that for astronomy education having a full sky projection is critical. The whole point of a planetarium is to immerse the audience in a full simulation of the night sky so that three dimensional concepts can be experienced first hand. Having empty black areas in the sky makes both teaching and learning in a planetarium more difficult for obvious reasons. Here is a visual comparison of approximate sky coverage for 1.) a fulldome system such as a Digitarium, 2.) a spherical mirror system with a 4:3 aspect projector, and 3.) a truncated 4:3 aspect fisheye projection system. Red areas are areas with no projection coverage. 
How does your Digitarium Gamma or Epsilon Portable compare to the Digital Starlab projector?Based on publicly available information and staff viewing of the Digital Starlab at the March, 2010 NSTA National Conference, these are the most important differences that we see:
* Please note that most of the advantages listed in the table above are opinions, which are by nature subjective. Our advice? See demonstrations of both the Digital Starlab and the Digitarium Gamma or Epsilon system. Talk to existing customers, take each for a test drive, and judge for yourself which system meets YOUR needs. How does a Digitarium system compare to an analog Starlab projector?The digital technology used in a Digitarium system offers many advantages over portable analog (pinhole) systems like Starlab. For example:
In short, a Digitarium system offers tremendously more flexibility, capability, and cost effectiveness than a portable analog system. See our products page for more information. Software FeaturesWhat software does a Digitarium system run? Can it run Starry Night, Celestia, The Sky, etc.?Digitarium systems run a Nightshade, an open source planetarium program. You can connect a separate computer to the projector to project other applications. However, the application needs to support fisheye rendering (polar projection) to be useful. You also must make sure that this use doesn't conflict with the software's license.
For example, retail versions of the planetarium software Starry Night can not be projected using a Digitarium system
because the Starry Night end user license agreement prohibits use with an audience. (There are dome versions which
can be used with an audience, but these can not be purchased independently of
certain planetarium systems.)
What differences are there between the Nightshade and Stellarium?Read more detail about Nightshade. From what culture(s) are the constellation labels, line drawings, and artwork?Currently we have line drawings, labels, and artwork for the 88 official Western constellations, as well as line drawings and labels for Polynesian, Chinese, Navajo, Lakota, Inuit, Norse, and ancient Egyptian constellations. We plan to add constellations from more cultures. When available, customers will be able to download the changes using the Digitarium system's software update feature.I don't know anything about the Linux operating system. Will I still be able to use a Digitarium system?You don't need to know a thing about Linux to run the system. You can't even tell what operating system is running, as the system is operated via a hand-held remote control.How do I get software and image updates?Hook your Digitarium system up to an ethernet network with Internet access (see the user manual if you need more information on this), bring up the menu, scroll down to “Administration,” then select Administration sub-item “Update me over the Internet.” The computer will do the rest for you. Software updates are free for the life of your system.What formats are supported by the Digitarium system's multimedia player?MPEG-2 is the best supported video format. If you have a question about a specific format, contact us.Are prerecorded shows available for the Digitarium system?An extensive list of fulldome shows and producers is maintained by Loch Ness Productions. These immersive video shows or segments are available from third party producers and distributors such as:
There is usually no technical reason why any fulldome video show could not be shown on a Digitarium system. It just needs to be sized appropriately and saved in a supported video format. Contact the show distributor for availability information. You can also create your own shows using the StratoScript scripting features of Nightshade on a desktop computer and play these back (including an audio track) on your system. Inflatable DomesCan I use my Starlab dome with a Digitarium system?Yes, a Digitarium system will work with any portable dome. However, if you project anything besides dark starfields you will see the extensive wrinkling in the silver StarLab domes. The reflective surface is also problematic. The Digitalis dome is specifically designed to be used with digital projectors. Our design has fewer wrinkles and no entrance tunnel interrupting the projection surface.Can I set up a Digitalis dome outside?No. Setting up a Digitalis dome outside is strongly discouraged. The dome is lightweight and could blow away, harming your audience or equipment, plus the outdoor environment could damage your dome.Is the Digitalis dome handicapped accessible?Yes. The dome does not have a solid floor; the wall of the dome wraps around and creates a skirt about 18 inches/45 cm wide which rests on the floor. To admit a person in a wheelchair, simply lift a side of the dome and push the wheelchair under. This process is much easier if you have a second person to help you lift the side of the dome. Once the dome is lowered back to the ground, it will reinflate fully in about one minute. What is the procedure for an emergency exit from a Digitalis dome?As mentioned above, Digitalis domes do not have a solid floor, so audiences can exit the dome very quickly by lifting the side and ducking under. Why do you sometimes use such a small dome at trade shows?We sometimes use a 9 foot diameter dome at conferences to economize on exhibit expenses so that we can keep our prices as low as possible. Keep in mind that a competitor displaying a larger dome usually is spending about four times as much on exhibit space, which adds up quickly.GeneralHow can I see a Digitarium system in use?Go to our see one page to review our conference schedule and demo policy.Can someone at Digitalis help me apply for a grant or sponsorship?Yes, you can contact Karrie Berglund, Director of Education, for help with funding proposals. However, please first read our funding page to see if it gives you the information you need. Note that we also offer a lease to own program that would allow you to spread the cost of a puchase over multiple budget years to make a purchase easier. What kind of maintenance is required by the projector and dome?Very little. The projector lens will need to be cleaned from time to time with a soft, lint-free cloth and alcohol (see your user manual for more information), and lamps will need to be replaced when they burn out or reach the end of their design life (the projector tracks usage information for you). You should have your system checked for dust accumulation once a year and cleaned if necessary. The dome can be cleaned with a damp sponge if needed.Is there a warranty for your products?All our equipment has a two year limited warranty, which you can read on the order form.PurchasingHow long does it take to get a Digitarium system or Digitalis dome?Typically one to eight weeks, depending on inventory levels. We try to stock all the products we sell. Contact us for a current turn around estimate.How do I find out if there is a local distributor in my country?All of our distributors are listed on our contact us page.I want to be a sales agent or distributor for your equipment. What do I need to do?Contact us to discuss the possibility. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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